More Grazing After The Frost:
Overseeding Winter Annuals On Warm-Season Grass Pastures
For a lot of sheep producers in the Southeastern United States, many of our pastures are largely warm-season grasses, mainly Bermuda grass, Bahia grass and crabgrass. These grasses are very productive during the summer months but quickly turn brown and lose nutritive quality after a killing frost.
To keep from feeding large amounts of hay during the winter, winter annual grasses and legumes can be successfully grown on these pastures to get some high quality grazing by late winter and early spring. The potential for these forages to be used in sheep production systems is great because they can fit into fall, winter and spring lambing systems or even for feeder lambs.
Winter Annual Grasses And Clovers
In the South, it is a blessing that the climate and soils allow for a variety of winter annual grasses and legumes to be grown. The major winter annual grasses are rye, wheat, and annual ryegrass. The major winter annual legumes are crimson clover, arrowleaf clover, ball clover and hairy vetch. These are all versatile enough to be sown together or separately.
Each of these forage species has a different growth curve or maturity date. The earliest of the grasses is rye, followed by wheat and lastly, annual ryegrass.
Of the legumes, crimson clover is the earliest and arrowleaf clover is the latest in the spring with ball clover and hairy vetch somewhere in between. The growing season for these forages when overseeded on warm season grass sods will go from February to June.
Before planting any of these forage species, consult with your extension service or your local feed store for a variety that works best in your area. For example, two annual ryegrass varieties that have been on the market for many years are Marshall and Gulf. In many trials, Marshall has been the better yielder in areas 100 miles north of the Gulf of Mexico. However, closer to the Gulf of Mexico, Marshall ryegrass succumbs to rust, whereas Gulf ryegrass tolerates rust and continues to produce well.
Many of the land grant universities conduct forage testing of different varieties to determine their yield potential, disease tolerance, and quality.
Successfully planting winter annuals depends on following a few rules. Rules include:
- Know your soil fertility
- Prepare the sod
- Sow the seed on the correct date and seed rate; and
- Use appropriate planting method.
- Winter annuals are generally very forgiving forages to plant—if you stay on top of these rules.
Just like with any crop, take a soil test to know the fertility of your soil and to add any soil amendments you might need before you plant. Lime is the most underutilized soil amendment in the South. These forages have their best production when soil pH is around 6.5 but most soils in the South are acidic in the low to mid-5s.
The legumes need a higher pH than grasses for good production.
Nitrogen is the most plant deficient nutrient but should be applied after winter annual grasses have gotten a good start and after a killing frost or in late winter. Don’t apply before a killing frost or your warm season grasses will get the benefit instead of the winter annuals. The legumes don’t need nitrogen as they can fix their own nitrogen from atmospheric nitrogen. Phosphorus and potassium once applied don’t move too much in soils used as pastures. Apply these nutrients according to soil test.
To give the winter annuals a fighting chance, reduce the existing vegetation. This may be done by hard grazing or by clipping close down to a height of two to three inches. This is extremely important in order to get a uniform stand of forage.
Bermuda grass, Bahia grass and crabgrass form dense sods that can crowd or shade out new seedlings. On some very thick sods, it may be necessary to lightly disk or run a harrow to beat the sod up a little bit prior to planting.
Plant on time with the correct amount of seed. Consult the table to determine the best times to plant and the amount of seed you will need.
Weather can cause some problems planting any crop, but it’s advisable to try to plant these winter annuals within the appropriate window of time. Planting too early results in problems of winter annuals surviving after germination. Autumns can be dry in the South and seedling death can occur. More important is that warm season grasses are still actively growing and shade out new seedlings. Planting too late can cause some problems in that seedlings die because of frost damage or your first grazing will be later than you intend.
The planting method should ensure adequate seed-to-soil contact. Fortunately, these forages can be planted easily by drilling or broadcasting.
Drilling has the nice advantage of getting a good seed-to-soil contact. When drilling, be sure not to sow seed to deep. Annual ryegrass and the clovers shouldn’t be planted deeper than a half-inch. Rye, wheat and hairy vetch are bigger seeds and can be planted up to one to two inches.
To be successful with broadcasting, the vegetation on the sod should be removed, the seed broadcasted and then the sod dragged with a harrow or drag. The seed may also be trampled in by the sheep if they are grazed in large concentrations. But this is often hard to do at this time of year, since many sheep producers are trying to flush ewes for breeding. Annual ryegrass and the clovers are more suited to broadcasting because of small seed size and shallow planting depth.
Management is critical to get good production from these forages. For best production, these forages should be allowed to reach a height of eight inches before grazing. For those who practice rotational grazing, it’s best to start grazing at eight to ten inches and stop at three to four-inch height. Allow three to four weeks of rest between grazings. If the sheep are going to be grazing the pasture all the time, try to stock the pasture to where grass height stays at an average of five to six inches. These forages have the ability to reseed but require that sheep be removed from pastures in late spring. A producer will have to weigh the risk of whether it is worth losing the extra grazing to get a crop for next year.
All of the winter annual forages are high quality. The digestible energy values are 70+ percent and crude protein at 15+ percent—more than adequate to meet all classes of sheep.
These forages can meet a niche for most sheep systems. For spring lambing, they arrive right on time for ewes entering lactation. They allow fall lambing flocks to get their ewes in shape prior to breeding and put extra weight on lambs. Winter-born lambs can be weaned directly onto winter annual pastures. Lambs make excellent gains on winter annual pastures. Weight gains with feeder lambs can be as high as a half-pound a day per lamb, with gains up to 700 pounds per acre.
Winter annual grasses and legumes are an important tool for sheep producers in the South. They provide the opportunity for earlier grazing in late winter or early spring with very high quality, productive pastures. By following the rules during planting and practicing good management, these forages allow sheep producers of different production systems to reap the benefits of good weight gains on pasture.